A sample drop cell based on gold microelectrodes obtained from split electronic chips

The electrochemical devices offer attractive characteristics for field measurements, including low cost, portability and easily of miniaturization. In this work, a one drop batch cell was fabricated on a platform with 14 gold microelectrodes obtained from disposable electronic chips packaged by surface-mount device (SMD) technology [1]. Fig 1 depicts the design of electrochemical cell. The fourteen gold microelectrodes (AuMEs) are distributed in an almost circular shape on polymeric platform, as can be seen on Fig 1G. Four AuMEs were interconnected in parallel to work as auxiliary electrode. A micro Ag/AgCl reference electrode was positioned in the central circle of the microelectrodes to measure the potentials of the working electrodes [2]. Ten AuMEs can be individually or in parallel addressed to operate as working electrode. The cell uses microvolume of 10 to 30 µL sample drops. Fig. 2 shows typical cyclic voltammograms with sigmoidal shape obtained with two AuMEs with different concentrations of [Fe(CN)6]3- in 0.10 mol L-1 KCl by using sample drops of 30 µL. The good proportionality between the anodic limiting current and [Fe(CN)6]3- concentration can be confirmed by calibration plot shown in the inset (R2 = 0.998). The repeatability of five CVs of 5 mmol L-1 [Fe(CN)6]3- obtained with a sample drop shown an RSD = 2 % while for different sample drops a RSD = 3% was found. The cell set up is simple, inexpensive and easy to operate, which are very attractive for field measurements